Separators for enhanced flooded batteries, batteries, and related methods

ABSTRACT

A battery separator has performance enhancing additives or coatings, fillers with increased friability, increased ionic diffusion, decreased tortuosity, increased wettability, reduced oil content, reduced thickness, decreased electrical resistance, and/or increased porosity. The separator in a battery reduces the water loss, lowers acid stratification, lowers the voltage drop, and/or increases the CCA. The separators include or exhibit performance enhancing additives or coatings, increased porosity, increased void volume, amorphous silica, higher oil absorption silica, higher silanol group silica, reduced electrical resistance, a shish-kebab structure or morphology, a polyolefin microporous membrane containing particle-like filler in an amount of 40% or more by weight of the membrane and ultrahigh molecular weight polyethylene having shish-kebab formations and the average repetition periodicity of the kebab formation from 1 nm to 150 nm, decreased sheet thickness, decreased tortuosity, separators especially well-suited for enhanced flooded batteries.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application which claims priority toU.S. Application Ser. No. 15/482,293, filed Apr. 7, 2017; which claimspriority to and the benefit of U.S. Provisional Patent App. No.62/319,959 filed Apr. 8, 2016.

FIELD

In accordance with at least selected embodiments, the present disclosureor invention is directed to novel or improved separators, batteryseparators, enhanced flooded battery separators, batteries, cells,and/or methods of manufacture and/or use of such separators, batteryseparators, enhanced flooded battery separators, cells, batteries,systems, methods, and/or vehicles using the same. In accordance with atleast certain embodiments, the present disclosure or invention isdirected to novel or improved battery separators, flooded lead acidbattery separators, or enhanced flooded lead acid battery separators forstarting lighting ignition (“SLI”) batteries, flooded batteries for deepcycle applications, and enhanced flooded batteries (“EFB”) and/orimproved methods of making and/or using such improved separators, cells,batteries, systems, vehicles, or any combination thereof. In accordancewith at least certain embodiments, the present disclosure or inventionis directed to an improved separator for enhanced flooded batteriesand/or improved methods of making and/or using such batteries havingsuch improved separators. In accordance with at least selectedembodiments, the present disclosure or invention is directed toseparators, particularly separators for enhanced flooded batterieshaving reduced electrical resistance and/or increased cold crankingamps. In addition, disclosed herein are methods, systems, and batteryseparators for enhancing battery life, reducing water loss, reducinginternal resistance, increasing wettability, reducing acidstratification, improving acid diffusion, improving cold cranking amps,improving uniformity, or any combination thereof in at least enhancedflooded batteries. In accordance with at least particular embodiments,the present disclosure or invention is directed to an improved separatorfor enhanced flooded batteries wherein the separator includesperformance enhancing additives or coatings, increased porosity,increased void volume, amorphous silica, higher oil absorption silica,higher silanol group silica, silica with an OH to Si ratio of 21:100 to35:100, reduced electrical resistance, a shish-kebab structure ormorphology, a polyolefin microporous membrane containing particle-likefiller in an amount of 40% or more by weight of the membrane andpolymer, such as ultrahigh molecular weight polyethylene, havingshish-kebab formations with extended chain crystal (shish formation) andfolded chain crystal (kebab formation) and the average repetitionperiodicity of the kebab formation from 1 nm to 150 nm, decreased sheetthickness, decreased tortuosity, and/or the like.

BACKGROUND

Enhanced flooded batteries (“EFB”) and absorbent glassmat (“AGM”)batteries have been developed to meet the expanding need for electricpower sources in idle start stop applications. EFB systems have similararchitecture to traditional flooded lead acid batteries, in whichpositive and/or negative electrodes are surrounded by a microporousseparator and submerged in a liquid electrolyte. AGM systems, on theother hand, do not contain free liquid electrolyte. Instead, theelectrolyte is absorbed into a glass fiber mat which is then layered ontop of the electrodes. Historically, AGM systems have been associatedwith higher discharge power, better cycle life, and greater coldcranking amps than flooded battery systems. However, AGM batteries aresignificantly more expensive to manufacture and are more sensitive toovercharging. As such, EFB systems remain an attractive option formobile and/or stationary power sources for some markets andapplications. Such power source and energy storage applications are asvaried as: flat-plate batteries; tubular batteries; vehicle SLI, andhybrid-electric vehicle ISS applications; deep cycle applications; golfcar or golf cart, and e-rickshaw batteries; batteries operating in apartial state of charge (“PSOC”); inverter batteries; and storagebatteries for renewable energy sources.

EFB systems may include one or more battery separators that separatesthe positive electrode from the negative electrode within a lead acidbattery cell. A battery separator may have two primary functions. First,a battery separator should keep the positive electrode physically apartfrom the negative electrode in order to prevent any electronic currentpassing between the two electrodes. Second, a battery separator shouldpermit ionic diffusion between the positive and negative electrodes withthe least possible resistance in order to generate a current. A batteryseparator can be made out of many different materials, but these twoopposing functions have been met well by a battery separator being madeof a porous nonconductor. With this structure, pores contribute to ionicdiffusion between electrodes, and a non-conducting polymeric networkprevents electronic shorting.

An EFB battery with increased discharge rate and cold cranking amperesor amps (“CCA”) would be able to displace AGM batteries. It is knownthat cold cranking amps are correlated with the internal resistance ofthe battery. It is therefore expected that lowering internal resistanceof an enhanced flooded battery will increase the cold cranking ampsrating. As such, there is a need for new battery separator and/orbattery technology to meet and overcome the challenges arising fromcurrent lead acid battery systems, especially to lower internalresistance and increase cold cranking amps in enhanced floodedbatteries.

SUMMARY

In accordance with at least selected embodiments, the present disclosureor invention may address the above issues or needs. In accordance withat least certain objects, the present disclosure or invention mayprovide an improved separator and/or battery which overcomes theaforementioned problems, for instance by providing enhanced floodedbatteries having reduced internal electrical resistance and increasedcold cranking amps.

In accordance with at least selected embodiments, the present disclosureor invention may address the above issues or needs and/or may providenovel or improved separators and/or enhanced flooded batteries. Inaccordance with at least selected embodiments, the present disclosure orinvention is directed to novel or improved separators, batteryseparators, enhanced flooded battery separators, batteries, cells,and/or methods of manufacture and/or use of such separators, batteryseparators, enhanced flooded battery separators, cells, and/orbatteries. In accordance with at least certain embodiments, the presentdisclosure or invention is directed to novel or improved batteryseparators, flooded lead acid battery separators, or enhanced floodedbattery separators for automobile applications, for idle start stop(“ISS”) batteries, for batteries with high power requirements, such asuninterrupted power supply (“UPS”) or valve regulated lead acid(“VRLA”), and/or for batteries with high CCA requirements, and/orimproved methods of making and/or using such improved separators, cells,batteries, systems, and/or the like. In accordance with at least certainembodiments, the present disclosure or invention is directed to animproved separator for enhanced flooded batteries and/or improvedmethods of using such batteries having such improved separators. Inaddition, disclosed herein are methods, systems and battery separatorsfor enhancing battery performance and life, reducing acidstratification, reducing internal electrical resistance, increasing coldcranking amps, and/or improving uniformity in at least enhanced floodedbatteries. In accordance with at least particular embodiments, thepresent disclosure or invention is directed to an improved separator forenhanced flooded batteries wherein the separator includes decreasedelectrical resistance, performance enhancing additives or coatings,improved fillers, increased porosity, decreased tortuosity, reducedthickness, reduced oil content, increased wettability, increased aciddiffusion, and/or the like.

In accordance with at least one embodiment, a microporous separator withdecreased tortuosity is provided. Tortuosity refers to the degree ofcurvature/turns that a pore takes over its length. Thus, a microporousseparator with decreased tortuosity will present a shorter path for ionsto travel through the separator, thereby decreasing electricalresistance. Microporous separators in accordance with such embodimentscan have decreased thickness, increased pore size, more interconnectedpores, and/or more open pores.

In accordance with at least certain selected embodiments, a microporousseparator with increased porosity, or a separator with a different porestructure whose porosity is not significantly different from a knownseparator, and/or decreased thickness is provided. An ion will travelmore rapidly though a microporous separator with increased porosity,increased void volume, reduced tortuosity, and/or decreased thickness,thereby decreasing electrical resistance. Such decreased thickness mayresult in decreased overall weight of the battery separator, which inturn decreases the weight of the enhanced flooded battery in which theseparator is used, which in turn decreases the weight of the overallvehicle in which the enhanced flooded battery is used. Such decreasedthickness may alternatively result in increased space for the positiveactive material (“PAM”) or the negative active material (“NAM”) in theenhanced flooded battery in which the separator is used.

In accordance with at least certain selected embodiments, a microporousseparator with increased wettability (in water or acid) is provided. Theseparator with increased wettability will be more accessible to theelectrolyte ionic species, thus facilitating their transit across theseparator and decreasing electrical resistance.

In accordance with at least one embodiment, a microporous separator withdecreased final oil content is provided. Such a microporous separatorwill also facilitate lowered ER (electrical resistance) in an enhancedflooded battery or system.

The separator may contain improved fillers that have increasedfriability, and that may increase the porosity, pore size, internal poresurface area, wettability, and/or the surface area of the separator. Insome embodiments, the improved fillers have high structural morphologyand/or reduced particle size and/or a different amount of silanol groupsthan previously known fillers and/or are more hydroxylated thanpreviously known fillers. The improved fillers may absorb more oiland/or may permit incorporation of a greater amount of processing oilduring separator formation, without concurrent shrinkage or compressionwhen the oil is removed after extrusion. The fillers may further reducewhat is called the hydration sphere of the electrolyte ions, enhancingtheir transport across the membrane, thereby once again lowering theoverall electrical resistance or ER of the battery, such as an enhancedflooded battery or system.

The filler or fillers may contain various species (such as polarspecies, such as metals) that increase the ionic diffusion, andfacilitate the flow of electrolyte and ions across the separator. Suchalso leads to decreased overall electrical resistance as such aseparator is used in a flooded battery, such as an enhanced floodedbattery.

The microporous separator further comprises a novel and improved poremorphology and/or novel and improved fibril morphology such that theseparator contributes to significantly decreasing the electricalresistance in a flooded lead acid battery when such a separator is usedin such a flooded lead acid battery. Such improved pore morphologyand/or fibril morphology may result in a separator whose pores and/orfibrils approximate a shish-kebab (or shish kabob) type morphology.Another way to describe the novel and improved pore shape and structureis a textured fibril morphology in which silica nodes or nodes of silicaare present at the kebab-type formations on the polymer fibrils (thefibrils sometimes called shishes) within the battery separator.Additionally, in certain embodiments, the silica structure and porestructure of a separator according to the present invention may bedescribed as a skeletal structure or a vertebral structure or spinalstructure, where silica nodes on the kebabs of polymer, along thefibrils of polymer, appear like vertebrae or disks (the “kebabs”), andsometimes are oriented substantially perpendicularly to, an elongatecentral spine or fibril (extended chain polymer crystal) thatapproximates a spinal column-like shape (the “shish”).

In some instances, the improved battery comprising the improvedseparator with the improved pore morphology and/or fibril morphology mayexhibit 20% lower, in some instances, 25% lower, in some instances, 30%lower electrical resistance, and in some instances, even more than a 30%drop in electrical resistance (“ER”) (which may reduce battery internalresistance) while such a separator retains and maintains a balance ofother key, desirable mechanical properties of lead acid batteryseparators. Further, in certain embodiments, the separators describedherein have a novel and/or improved pore shape such that moreelectrolyte flows through or fills the pores and/or voids as compared toknown separators.

In addition, the present disclosure provides improved enhanced floodedlead acid batteries comprising one or more improved battery separatorsfor an enhanced flooded battery, which separator combines for thebattery the desirable features of decreased acid stratification, loweredvoltage drop (or an increase in voltage drop durability), and increasedCCA, in some instances, more than 8%, or more than 9%, or in someembodiments, more than 10%, or more than 15%, increased CCA. Such animproved separator may result in an enhanced flooded battery whoseperformance matches or even exceeds the performance of an AGM battery.Such low electrical resistance separator may also be treated so as toresult in an enhanced flooded lead acid battery having reduced waterloss.

The separator may contain one or more performance enhancing additives,such as a surfactant, along with other additives or agents, residualoil, and fillers. Such performance enhancing additives can reduceseparator oxidation and/or even further facilitate the transport of ionsacross the membrane contributing to the overall lowered electricalresistance for the enhanced flooded battery described herein.

The separator for a lead acid battery described herein may comprise apolyolefin microporous membrane, wherein the polyolefin microporousmembrane comprises: polymer, such as polyethylene, such as ultrahighmolecular weight polyethylene, particle-like filler, and processingplasticizer (optionally with one or more additional additives oragents). The polyolefin microporous membrane may comprise theparticle-like filler in an amount of 40% or more by weight of themembrane. And the ultrahigh molecular weight polyethylene may comprisepolymer in a shish-kebab formation comprising a plurality of extendedchain crystals (the shish formations) and a plurality of folded chaincrystals (the kebab formations), wherein the average repetition orperiodicity of the kebab formations is from 1 nm to 150 nm, preferably,from 10 nm to 120 nm, and more preferably, from 20 nm to 100 nm (atleast on portions of the rib side of the separator).

The average repetition or periodicity of the kebab formations iscalculated in accordance with the following definition:

-   -   The surface of the polyolefin microporous membrane is observed        using a scanning electron microscope (“SEM”) after being        subjected to metal vapor deposition, and then the image of the        surface is taken at, for example 30,000 or 50,000-fold        magnification at 1.0 kV accelerating voltage.    -   In the same visual area of the SEM image, at least three regions        where shish-kebab formations are continuously extended in the        length of at least 0.5 μm or longer are indicated. Then, the        kebab periodicity of each indicated region is calculated.    -   The kebab periodicity is specified by Fourier transform of        concentration profile (contrast profile) obtained by projecting        in the vertical direction to the shish formation of the        shish-kebab formation in each indicated region to calculate the        average of the repetition periods.    -   The images are analyzed using general analysis tools, for        example, MATLAB (R2013a).    -   Among the spectrum profiles obtained after the Fourier        transform, spectrum detected in the short wavelength region are        considered as noise. Such noise is mainly caused by deformation        of contrast profile. The contrast profiles obtained for        separators in accordance with the present invention appear to        generate square-like waves (rather than sinusoidal waves).        Further, when the contrast profile is a square-like wave, the        profile after the Fourier transform becomes a Sine function and        therefore generates plural peaks in the short wavelength region        besides the main peak indicating the true kebab periodicity.        Such peaks in the short wavelength region can be detected as        noise.

In some embodiments, the separator for a lead acid battery describedherein comprises a filler selected from the group consisting of silica,precipitated silica, fumed silica, and precipitated amorphous silica;wherein the molecular ratio of OH to Si groups within said filler,measured by ²⁹Si-NMR, is within a range of from 21:100 to 35:100, insome embodiments, 23:100 to 31:100, in some embodiments, 25:100 to29:100, and in certain preferred embodiments, 27:100 or higher. Silanolgroups change a silica structure from a crystalline structure to anamorphous structure, since the relatively stiff covalent bond network ofSi—O has partially disappeared. The amorphous-like silicas such asSi(—O—Si)₂(—OH)₂ and Si(—O—Si)₃(—OH) have plenty of distortions, whichmay function as various oil absorption points. Therefore oilabsorbability becomes high when the amount of silanol groups (Si—OH) isincreased for the silica. Additionally, the separator described hereinmay exhibit increased hydrophilicity and/or may have higher void volumeand/or may have certain aggregates surrounded by large voids when itcomprises a silica comprising a higher amount of silanol groups and/orhydroxyl groups than a silica used with a known lead acid batteryseparator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 includes a depiction of the pore size distribution of anembodiment of the instant invention, a lower ER separator, in comparisonwith a conventional separator.

FIG. 2 includes a depiction of the oxidation stability of an embodimentof the instant invention (sometimes referred to as the “EFS” product, anEnhanced Flooded Separator™) in comparison with a conventionalseparator. In the battery overcharge test, after 1,000 hours, theseparator according to the present invention is less brittle than thecontrol separator and thus exhibits higher elongation.

FIG. 3 includes a depiction of the electrical resistance data ofseparators prepared with different silica fillers. The silica fillersdiffer in their intrinsic oil absorption. In certain embodiments of thepresent invention, the improved separator is formed using a silicahaving an intrinsic oil absorption value of about 175-350 ml/100 g, insome embodiments, 200-350 ml/100 g, in some embodiments, 250-350 ml/100gm, and in some further embodiments, 260-320 ml/100 g, though other oilabsorption values are possible as well.

FIG. 4 includes a depiction of the electrical resistance data ofseparators prepared with different process oils. The oils differ intheir aniline point.

FIG. 5 includes a depiction of acid stratification (%) versus Hgporosity (%) for separators according to the present invention.

FIG. 6 includes a depiction of ER boil versus backweb thickness.

FIG. 7 includes an SEM image of an embodiment of a separator of theinstant invention at 50,000× magnification, while FIGS. 8A and 8B areSEM images of the same separator at 10,000× magnification. In the SEM ofFIG. 7 , the shish kebab-type morphology or textured fibril-typestructure is observed, and the pore and silica structure leaves certaincavities or pores with much less polymer webbing (in some cases almostno polymer webbing) and much fewer thick fibrils or strands ofhydrophobic polymer (in some cases almost no or no thick fibrils orstrands of hydrophobic polymer). Electrolyte and/or acid, and thereforeions pass much more readily through the pore structure observed in thisseparator shown in FIGS. 7-8B. The structure of the separator providesfree space in which acid freely moves.

FIGS. 9A and 9B include depictions of the pore size distribution ofseparator embodiments. FIG. 9A is for a control separator, while FIG. 9Bis for a low ER separator with desirable mechanical properties accordingto one embodiment of the present invention. Note that FIG. 9B can alsobe seen as part of FIG. 1 .

FIG. 10 includes a comparison of various pore size measurements for aseparator according to the instant invention with a conventionalseparator. In FIG. 10 , the bubble flow rate difference is significantin that it is measuring the through-pores of the separator and measuringthe ability of such through-pores to functionally transport ions all theway through the separator. While the mean pore size and the minimum poresize are not significantly different, the maximum pore size is greaterfor the separator according to the present invention, and the bubbleflow rate is significantly higher for the separator according to thepresent invention.

FIGS. 11A and 11B show porometry data and a depiction of the flow ofliquid through a separator in accordance with an embodiment of theinvention (FIG. 11A) in comparison with flow of liquid through a controlseparator (FIG. 11B).

FIGS. 12A and 12B include two SEMs at two different magnifications of acontrol separator made by Daramic, LLC. In these SEMs, relatively thickfibrils or strands of hydrophobic polymer are observed.

FIGS. 13A and 13B include two SEMs at two different magnifications ofanother control separator made by Daramic, LLC. In these SEMs, areasthat appear to be polymer webbing can be observed.

FIG. 14A includes an SEM of a separator formed according to anembodiment of the present invention, wherein the shish-kebab polymerformation(s) are observed.

FIGS. 14B and 14C portray how a Fourier transform contrast profile(spectrum at the bottom, FIG. 14C) helps determine the repetition orperiodicity of the shish-kebab formations (see shish-kebab formation atthe top, FIG. 14B) in the separator.

FIG. 15A includes an SEM of the inventive separator of Example 1.

FIGS. 15B, 15C, and 15D include Welch Power Spectral Density Estimategraphs showing results from the FTIR spectral tests performed on thethree shish-kebab regions (Nos. 1, 2, and 3), respectively, shown andmarked in FIG. 15A, wherein the x-axis of the graphs in FIGS. 15B, 15C,and 15D is normalized frequency (xπrad/sample), and wherein the y-axisof those graphs=power/frequency (dB/rad/sample).

FIGS. 16A, 16B, 16C, and 16D are similar to FIGS. 15A-15D, respectively,but are representative of the inventive separator of Example 2.

FIGS. 17A, 17B, 17C, and 17D are similar to FIGS. 15A-15D, respectively,but are representative of the inventive separator of Example 3.

FIGS. 18A, 18B, 18C, and 18D are similar to FIGS. 15A-15D, respectively,but are representative of the inventive separator of Example 4.

FIGS. 19A, 19B, 19C, and 19D are similar to FIGS. 15A-15D, respectively,but are representative of the inventive separator of Example 5.

FIGS. 20A, 20B, 20C, and 20D are similar to FIGS. 15A-15D, respectively,but are representative of the separator of Comparative Example 1 (CE1).

FIGS. 21A and 21B are similar to FIGS. 15A and 15B, respectively, butare representative of the separator of Comparative Example 2.

FIG. 22 is an SEM of the separator of Comparative Example 3.

FIGS. 23A and 23B include ²⁹Si-NMR spectra for Comparative Example 4(FIG. 23A) and Example 1 (FIG. 23B), respectively.

FIGS. 24A and 24B include deconvolution of the component peaks from thespectra of FIGS. 23A and 23B to determine the Q₂:Q₃:Q₄ ratios for theseparator samples of CE4 (FIG. 24A) and Example 1 (FIG. 24B),respectively.

FIG. 25 illustrates a tip used to puncture test separators.

FIG. 26A is a schematic rendering of an elongation test sample.

FIG. 26B illustrates a sample holder for an elongation test.

FIG. 27 shows a Nuclear Magnetic Resonance (“NMR”) tube with separatorsamples submerged in D₂O.

FIG. 28 shows the diffusion coefficients at −10° C. at Δ=20 ms for asolution of H₂SO₄ only, a reference separator, an inventive embodimentseparator, and an AGM separator.

FIGS. 29A and 29B illustrate a pore size distribution of an inventiveembodiment compared to that of a commercially available separator.

FIG. 30 depicts the pore diameter distribution of an inventiveembodiment separator.

FIG. 31 is a chart that describes the dispersion of a new silica fillerwithin an inventive embodiment separator and a standard silica within acommercially available separator.

FIGS. 32A and 32B depict the size of a standard silica with that of asilica used in an inventive embodiment of the present invention.

FIG. 33 shows the size of a new silica before and after sonication.

FIGS. 34A and 34B show the silica size before and after sonication, andFIGS. 34A and 34B depict the particle size distribution of the newsilica and standard silica before sonication and after 30 seconds andafter 60 seconds of sonication.

DETAILED DESCRIPTION

Composition

The inventive separator is preferably a porous membrane made of naturalor synthetic materials, such as polyolefin, polyethylene, polypropylene,phenolic resin, PVC, rubber, synthetic wood pulp (SWP), glass fibers,synthetic fibers, cellulosic fibers, or combinations thereof, morepreferably a microporous membrane made from one or more thermoplasticpolymers. The thermoplastic polymer may, in principle, include allacid-resistant thermoplastic materials suitable for use in lead acidbatteries. The preferred thermoplastic polymers include polyvinyls andpolyolefins. The polyvinyls include, for example, polyvinyl chloride(PVC). The polyolefins include, for example, polyethylene, includingultrahigh molecular weight polyethylene (UHMWPE), and polypropylene. Onepreferred embodiment may include UHMWPE and a filler. In general, thepreferred separator may be made by mixing, in an extruder, filler,thermoplastic polymer, and processing plasticizer. The processingplasticizer may be a processing oil, such as petroleum oil,paraffin-based mineral oil, mineral oil, and any combination thereof.

The microporous separator is preferably made of a polyolefin, such aspolypropylene, ethylene-butene copolymer, and preferably polyethylene,more preferably high molecular weight polyethylene, i.e. polyethylenehaving a molecular weight of at least 600,000, even more preferablyultrahigh molecular weight polyethylene, i.e. polyethylene having amolecular weight of at least 1,000,000, in particular more than4,000,000, and most preferably 5,000,000 to 8,000,000 (measured byviscosimetry and calculated by Margolie's equation), a standard loadmelt index of substantially 0 (measured as specified in ASTM D 1238(Condition E) using a standard load of 2,160 g) and a viscosity numberof not less than 600 ml/g, preferably not less than 1,000 ml/g, morepreferably not less than 2,000 ml/g, and most preferably not less than3,000 ml/g (determined in a solution of 0.02 g of polyolefin in 100 g ofdecalin at 130° C.).

In accordance with at least one embodiment, the separator is made up ofan ultrahigh molecular weight polyethylene (UHMWPE) mixed with aprocessing oil and filler. In accordance with at least one otherembodiment, the separator is made up of an ultrahigh molecular weightpolyethylene (UHMWPE) mixed with a processing oil, additive and filler.

In certain selected embodiments, the separator can be prepared bycombining, by weight, about 5-15% polymer, in some instances, about 10%polymer, about 10-60% filler, in some instances, about 30% filler, andabout 30-80% processing oil, in some instances, about 60% processingoil. In other embodiments, the filler content is reduced, and the oilcontent is higher, for instance, greater than about 61%, 62%, 63%, 64%,65%, 66%, 67%, 68%, 69% or 70% by weight. The filler:polymer ratio (byweight) can be about (or can be between about these specific ranges)such as 2:1, 2.5:1, 3:1, 3.5:1, 4.0:1. 4.5:1, 5.0:1, 5.5:1 or 6:1. Thefiller:polymer ratio (by weight) can be from about 1.5:1 to about 6:1,in some instances, 2:1 to 6:1, from about 2:1 to 5:1, from about 2:1 to4:1, and in some instances, from about 2:1 to about 3:1.

Additives Introduction and Backweb Thickness

The mixture may also include minor amounts of other additives or agentsas is common in the separator arts, such as surfactants, wetting agents,colorants, antistatic additives, antioxidants, and/or the like, and anycombination thereof. The mixture may be extruded into the shape of aflat sheet, or a sheet having ribs or other protrusions on one or bothsides of the sheet. After the separator is extruded, it can be furthercompressed using either a machine press or calendar stack or roll. Thepress or calendar may be engraved to impart ribs, grooves, serrations,serrated ribs, embossments and the like into the microporous separator.

According to certain selected embodiments, the separator has a backwebthickness that is less than about 150 μm, 140 μm, 130 μm, 120 μm, 110μm, 100 μm, 90 μm, 80 μm, 70 μm, 60 μm, 50 μm, or 40 μm. In certainselected embodiments, the backweb thickness is from about 100-500 μm,150-400 μm, 150-350 μm, 150-300 μm, or 175-300 μm, or 200-300 μm. Insome embodiments, the backweb thickness is about 250 μm; in others, thebackweb thickness is about 200 μm; in still others, the backwebthickness is about 400 μm. In some selected embodiments, the separatorhas a backweb thickness from about 200±35 μm, 200-250 μm, 50-150 μm,75-150 μm, 75-125 μm, 75-100 μm, 100-125 μm, or 50-100 μm.

Ribs

In certain embodiments, the separator can have ribs on at least oneface. The ribs can facilitate processing during folding and cuttingsteps, decrease acid stratification, and/or promote acid mixing andincrease acid diffusion through the battery system. In accordance withat least another object of the present invention, there is provided aporous membrane with cross-ribs. Cross-ribs refer to ribs which extendin a direction other than the vertical edges of the separator. In someinstances, cross-ribs are perpendicular to, or extend in a directionother than, the direction in which the main ribs of the separatorextend. In some embodiments, cross-ribs are present on a separator evenwhen it does not include any main ribs. In some embodiments, main ribsare located on one surface of the microporous membrane separator, whilecross-ribs (sometimes referred to as negative cross-ribs) are located onanother surface of the microporous membrane separator. In someembodiments of the present invention, the main ribs or major ribs have aheight in the range of about 5 μm to about 1.5 mm. In some embodimentsof the present invention, the cross-ribs can have a rib height of atleast 0.005 mm, 0.01 mm, 0.025 mm, 0.05 mm, 0.075 mm, 0.1 mm, 0.2 mm,0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or 1.0 mm. Theseparator can have a cross-rib height between 0.005-1.0 mm, 0.01-0.5 mm,0.025-0.5 mm, 0.05-0.5 mm, 0.075-0.5 mm, 0.1-0.5 mm, 0.2-0.4 mm, 0.3-0.5mm, 0.4-0.5 mm.

Filler

The separator can contain a filler having a high structural morphology.Exemplary fillers can include: dry finely divided silica; precipitatedsilica; amorphous silica; highly friable silica; alumina; talc; fishmeal; fish bone meal; and the like, and any combination thereof. Incertain preferred embodiments, the filler is one or more silicas. Highstructural morphology refers to increased surface area. The filler canhave a high surface area, for instance, greater than 100 m²/g, 110 m²/g,120 m²/g, 130 m²/g, 140 m²/g, 150 m²/g, 160 m²/g, 170 m²/g, 180 m²/g,190 m²/g, 200 m²/g, 210 m²/g, 220 m²/g, 230 m²/g, 240 m²/g, or 250 m²/g.In some embodiments, the filler (e.g., silica) can have a surface areafrom 100-300 m²/g, 125-275 m²/g, 150-250 m²/g, or preferably 170-220m²/g. Surface area can be assessed using TriStar 3000™ for multipointBET nitrogen surface area. High structural morphology permits the fillerto hold more oil during the manufacturing process. For instance, afiller with high structural morphology has a high level of oilabsorption, for instance, greater than about 150 ml/100 g, 175 ml/100 g,200 ml/100 g, 225 ml/100 g, 250 ml/100 g, 275 ml/100 g, 300 ml/100 g,325 ml/100 g, or 350 ml/100 g. In some embodiments the filler (e.g.,silica) can have an oil absorption from 200-500 ml/100 g, 200-400 ml/100g, 225-375 ml/100 g, 225-350 ml/100 g, 225-325 ml/100 g, preferably250-300 ml/100 g. In some instances, a silica filler is used having anoil absorption of 266 ml/100 g. Such a silica filler has a moisturecontent of 5.1%, a BET surface area of 178 m²/g, an average particlesize of 23 μm, a sieve residue 230 mesh value of 0.1%, and a bulkdensity of 135 g/L.

Silica with relatively high levels of oil absorption and relatively highlevels of affinity for mineral oil becomes desirably dispersible in themixture of polyolefin (such as polyethylene) and mineral oil whenforming a lead acid battery separator of the type shown herein. In thepast, some separators have experienced the detriment of poordispersibility caused by silica aggregation when large amounts of silicaare used to make such separators or membranes. In at least certain ofthe inventive separators shown and described herein, the polyolefin,such as polyethylene, forms a shish-kebab structure, since there are fewsilica aggregations or agglomerates that inhibit the molecular motion ofthe polyolefin at the time of cooling the molten polyolefin. All of thiscontributes to improved ion permeability through the resulting separatormembrane, and the formation of the shish-kebab structure or morphologymeans that mechanical strength is maintained or even improved while alower overall ER separator is produced.

In some selected embodiments, the filler has an average particle size nogreater than 25 μm, in some instances, no greater than 22 μm, 20 μm, 18μm, 15 μm, or 10 μm. In some instances, the average particle size of thefiller particles (such as silica) is 15-25 μm. The particle size of thesilica filler contributes to the oil absorption of the silica and/or thesurface area of the silica filler.

In some preferred embodiments, the silica used to make the inventiveseparators has an increased amount of or number of surface silanolgroups (surface hydroxyl groups) compared with silica fillers usedpreviously to make lead acid battery separators. For example, the silicafillers that may be used with certain preferred embodiments herein maybe those silica fillers having at least 10%, at least 15%, at least 20%,at least 25%, at least 30%, or at least 35% more silanol and/or hydroxylsurface groups compared with known silica fillers used to make knownpolyolefin lead acid battery separators.

The ratio (Si—OH)/Si of silanol groups (Si—OH) to elemental silicon (Si)can be measured, for example, as follows.

1. Freeze-crush a polyolefin microporous membrane (where certaininventive membranes contain a certain variety of oil-absorbing silicaaccording to the present invention), and prepare the powder-like samplefor the solid-state nuclear magnetic resonance spectroscopy (²⁹Si-NMR).

2. Perform the ²⁹Si-NMR to the powder-like sample, and observe thespectrums including the Si spectrum strength which is directly bondingto a hydroxyl group (Spectrum: Q₂ and Q₃) and the Si spectrum strengthwhich is only directly bonding to an oxygen atom (Spectrum: Q₄), whereinthe molecular structure of each NMR peak spectrum can be delineated asfollows:

-   -   Q₂: (SiO)₂—Si*—(OH)₂: having two hydroxyl groups    -   Q₃: (SiO)₃—Si*—(OH): having one hydroxyl group    -   Q₄: (SiO)₄—Si*: All Si bondings are SiO

Where Si* is proved element by NMR observation.

3. The conditions for ²⁹Si-NMR used for observation are as follows:

-   -   Instrument: Bruker BioSpin Avance 500    -   Resonance Frequency: 99.36 MHz    -   Sample amount: 250 mg    -   NMR Tube: 7 my    -   Observing Method: DD/MAS    -   Pulse Width: 45°    -   Repetition time: 100 sec    -   Scans: 800    -   Magic Angle Spinning: 5,000 Hz    -   Chemical Shift Reference: Silicone Rubber as −22.43 ppm        (External Ref)

4. Numerically, separate peaks of the spectrum, and calculate the arearatio of each peak belonging to Q₂, Q₃ and Q₄. After that, based on theratios, calculate the molar ratio of hydroxyl groups (—OH) bondingdirectly to Si. The conditions for the numerical peak separation isconducted in the following manner:

-   -   Fitting region: −80 to −130 ppm    -   Initial peak top: −93 ppm for Q₂, −101 ppm for Q₃, −111 ppm for        Q₄, respectively.    -   Initial full width half maximum: 400 Hz for Q₂, 350 Hz for Q₃,        450 Hz for Q₄, respectively.    -   Gaussian function ratio: 80% at initial and 70 to 100% while        fitting.

5. The peak area ratios (Total is 100) of Q₂, Q₃, and Q₄ are calculatedbased on the each peak obtained by fitting. The NMR peak areacorresponded to the molecular number of each silicate bonding structure(thus, for the Q₄ NMR peak, four Si—O—Si bonds are present within thatsilicate structure; for the Q₃ NMR peak, three Si—O—Si bonds are presentwithin that silicate structure while one Si—OH bond is present; and forthe Q₂ NMR peak, two Si—O—Si bonds are present within that silicatestructure while two Si—OH bonds are present). Therefore each number ofthe hydroxyl group (—OH) of Q₂, Q₃, and Q₄ is multiplied by two (2) one(1), and zero (0), respectively. These three results are summed. Thesummed value displays the mole ratio of hydroxyl groups (—OH) directlybonding to Si.

In some selected embodiments, use of the fillers described above permitsthe use of a greater proportion of processing oil during the extrusionstep. As the porous structure in the separator is formed, in part, byremoval of the oil after the extrusion, higher initial absorbed amountsof oil results in higher porosity or higher void volume. Whileprocessing oil is an integral component of the extrusion step, oil is anon-conducting component of the separator. Residual oil in the separatorprotects the separator from oxidation when in contact with the positiveelectrode. The precise amount of oil in the processing step may becontrolled in the manufacture of conventional separators. Generallyspeaking, conventional separators are manufactured using 50-70%processing oil, in some embodiments, 55-65%, in some embodiments,60-65%, and in some embodiments, about 62% by weight processing oil.Reducing oil below about 59% is known to cause burning due to increasedfriction against the extruder components. However, increasing oil muchabove the prescribed amount may cause shrinking during the drying stage,leading to dimensional instability. Although previous attempts toincrease oil content resulted in pore shrinkage or condensation duringthe oil removal, separators prepared as disclosed herein exhibitminimal, if any, shrinkage and condensation during oil removal. Thus,porosity can be increased without compromising pore size and dimensionalstability, thereby decreasing electrical resistance.

In certain selected embodiments, the use of the filler described aboveallows for a reduced final oil concentration in the finished separator.Since oil is a non-conductor, reducing oil content can increase theionic conductivity of the separator and assist in lowering the ER of theseparator. As such, separators having reduced final oil contents canhave increased efficiency. In certain selected embodiments are providedseparators having a final processing oil content (by weight) less than20%, for example, between about 14% and 20%, and in some particularembodiments, less than 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%,9%, 8%, 7%, 6%, or 5%.

Friability

In certain selected embodiments, the filler can be an alumina, talc,silica, or a combination thereof. In some embodiments, the filler can bea precipitated silica, and in some embodiments, the precipitated silicais amorphous silica. In some embodiments, it is preferred to useaggregates and/or agglomerates of silica which allow for a finedispersion of filler throughout the separator, thereby decreasingtortuosity and electrical resistance. In certain preferred embodiments,the filler (e.g., silica) is characterized by a high level offriability. Good friability enhances the dispersion of the fillerthroughout the polymer during extrusion of the microporous membrane,enhancing porosity and thus overall ionic conductivity through theseparator.

Friability may be measured as the ability, tendency or propensity of thesilica particles or material (aggregates or agglomerates) to be brokendown into smaller sized and more dispersible particles, pieces orcomponents. As shown on the left side of FIG. 34 , the NEW silica ismore friable (is broken down into smaller pieces after 30 seconds andafter 60 seconds of sonication) than the STANDARD silica. For example,the NEW silica had a 50% volume particle diameter of 24.90 um at 0seconds sonication, 5.17 um at 30 seconds and 0.49 um at 60 seconds.Hence, at 30 seconds sonication there was over a 50% reduction in size(diameter) and at 60 seconds there was over a 75% reduction in size(diameter) of the 50% volume silica particles. Hence, one possiblypreferred definition of “high friability” may be at least a 50%reduction in average size (diameter) at 30 seconds of sonication and atleast a 75% reduction in average size (diameter) at 60 seconds ofsonication of the silica particles (or in processing of the resin silicamix to form the membrane). In at least certain embodiments, it may bepreferred to use a more friable silica, and may be even more preferredto use a silica that is friable and multi-modal, such as bi-modal ortri-modal, in its friability. With reference to FIG. 34 , the STANDARDsilica appears single modal in it friability or particle sizedistribution, while the NEW silica appears more friable, and bi-modal(two peaks) at 30 seconds sonication and tri-modal (three peaks) at 60seconds sonication. Such friable and multi-modal particle size silica orsilicas may provide enhanced membrane and separator properties.

The use of a filler having one or more of the above characteristicsenables the production of a separator having a higher final porosity.The separators disclosed herein can have a final porosity greater than60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, or 70%. Porosity maybe measured using gas adsorption methods. Porosity can be measured byBS-TE-2060.

In some selected embodiments, the microporous separator can have agreater proportion of larger pores while maintaining the average poresize no greater than about 1 μm, 0.9 μm, 0.8 μm, 0.7 μm, 0.6 μm, 0.5 μm,or 0.1 μm.

In accordance with at least one embodiment, the separator is made up ofpolyethylene, such as an ultrahigh molecular weight polyethylene(“UHMWPE”), mixed with a processing oil and filler as well as anydesired additive. In accordance with at least one other embodiment, theseparator is made up of an ultrahigh molecular weight polyethylene(UHMWPE) mixed with a processing oil and talc. In accordance with atleast one other embodiment, the separator is made up of UHMWPE mixedwith a processing oil and silica, for instance, precipitated silica, forinstance, amorphous precipitated silica. The additive can then beapplied to the separator via one or more of the techniques describedabove.

Besides reducing electrical resistance and increasing cold crankingamps, preferred separators are also designed to bring other benefits.With regard to assembly, the separators are more easily passed throughprocessing equipment, and therefore more efficiently manufactured. Toprevent shorts during high speed assembly and later in life, theseparators have superior puncture strength and oxidation resistance whencompared to standard PE separators. Combined with reduced electricalresistance and increased cold cranking amps, battery manufacturers arelikely to find improved and sustained electrical performance in theirbatteries with these new separators.

Electrical Resistance

In certain selected embodiments, the disclosed separators exhibitdecreased electrical resistance, for instance, an electrical resistanceno greater than about 200 mΩ·cm², 180 mΩ·cm², 160 mΩ·cm², 140 mΩ·cm²,120 mΩ·cm², 100 mΩ·cm², 80 mΩ·cm², 60 mΩ·cm², 50 mΩ·cm², 40 mΩ·cm², 30mΩ·cm², or 20 mΩ·cm². In various embodiments, the separators describedherein exhibit about a 20% or more reduction in ER compared with a knownseparator of the same thickness. For example, a known separator may havean ER value of 60 mΩ·cm²; thus, a separator according to the presentinvention at the same thickness would have an ER value of less thanabout 48 mΩ·cm².

To test a sample separator for ER testing evaluation in accordance withthe present invention, it must first be prepared. To do so, a sampleseparator is preferably submerged in a bath of demineralized water, thewater is then brought to a boil and the separator is then removed after10 minutes in the boiling demineralized water bath. After removal,excess water is shaken off the separator and then placed in a bath ofsulfuric acid having a specific gravity of 1.280 at 27° C.±1° C. Theseparator is soaked in the sulfuric acid bath for 20 minutes. Theseparator is then ready to be tested for electrical resistance.

Puncture Resistance

In certain selected embodiments, exemplary separators may becharacterized with an increased puncture resistance. For instance apuncture resistance of approximately 9 N or higher, 9.5 N or higher, 10N or higher, 10.5 N or higher, 11 N or higher, 11.5 N or higher 12 N orhigher, 12.5 N or higher, 13 N or higher, 13.5 N or higher, 14 N orhigher, 14.5 N or higher, 15 N or higher, 15.5 N or higher, 16 N orhigher, 16.5 N or higher, 17 N or higher, 17.5 N or higher, 18 N orhigher, 18.5 N or higher, 19 N or higher, 19.5 N or higher, or 20 N orhigher. In certain embodiments, exemplary separators may be preferablydefined with a puncture resistance of approximately 9 N-20 N or higher,or more preferably approximately 12 N-20 N or higher.

The puncture resistance may be measured as the force required topuncture the porous membrane utilizing the tip 100 as generally depictedin FIG. 25 . The puncture base in which the porous membrane is supportedwhile the tip 100 punctures the membrane may generally be described as abase having a 6.5 mm diameter straight hole with a 10 mm depth. Thetravel limit of the tip may be approximately 4 mm-8 mm below thepuncture base surface. The puncture tip 100 is linearly moved into themembrane at a rate of approximately 5 mm/s.

Additives

The separator may contain one or more performance enhancing additives,such as surfactants, wetting agents, colorants, antistatic additives,antioxidants, and/or the like, and any combination thereof. Theperformance enhancing additive may preferably be a surfactant. Certainsuitable surfactants are nonionic while other suitable surfactants areanionic. The use of these certain suitable surfactants in conjunctionwith the inventive separators described herein can lead to even furtherimproved separators that, when used in a lead acid battery, lead toreduced water loss for that lead acid battery. Suitable surfactantsinclude surfactants such as salts of alkyl sulfates; alkylarylsulfonatesalts; alkylphenol-alkylene oxide addition products; soaps;alkyl-naphthalene-sulfonate salts; one or more sulfo-succinates, such asan anionic sulfo-succinate; dialkyl esters of sulfo-succinate salts;quaternary amines; block copolymers of ethylene oxide and propyleneoxide; and salts of mono and dialkyl phosphate esters. The additive canbe a non-ionic surfactant such as polyol fatty acid esters,polyethoxylated esters, polyethoxylated alcohols, alkyl polysaccharidessuch as alkyl polyglycosides and blends thereof, amine ethoxylates,sorbitan fatty acid ester ethoxylates, organosilicone based surfactants,ethylene vinyl acetate terpolymers, ethoxylated alkyl aryl phosphateesters and sucrose esters of fatty acids.

The battery separators can be provided in various ways with theadditive(s), agent(s), and/or filler(s). The additive or additives canfor example be applied to the separator when it is finished (e.g., afterthe extraction of the plasticizer (e.g., processing oil)) and/or addedto the mixture used to extrude and ultimately produce the separator.According to certain preferred embodiments, the additive or a solutionof the additive is applied to the surface of the separator. This variantis suitable in particular for the application of non-thermostableadditives and additives which are soluble in the solvent used for thesubsequent extraction. Particularly suitable as solvents for theadditives according to the invention are low-molecular-weight alcohols,such as methanol and ethanol, as well as mixtures of these alcohols withwater. The application can take place on the side facing the negativeelectrode, the side facing the positive electrode or on both sides ofthe separator. Application can also take place during the extraction ofthe pore forming agent while in a solvent bath.

Certain embodiments of separators according to the present invention donot incorporate an additive such as a non-ionic surfactant or anionicsurfactant. In other embodiments, an additive (such as a non-ionicsurfactant, or an anionic surfactant) can be present at a density of atleast 0.5 g/m², 1.0 g/m², 1.5 g/m², 2.0 g/m², 2.5 g/m², 3.0 g/m², 3.5g/m², 4.0 g/m², 4.5 g/m², 5.0 g/m², 5.5 g/m², 6.0 g/m², 6.5 g/m², 7.0g/m², 7.5 g/m², 8.0 g/m², 8.5 g/m², 9.0 g/m², 9.5 g/m², or 10.0 g/m².The additive can be present on the separator at a density between 0.5-10g/m², 1.0-10.0 g/m², 1.5-10.0 g/m², 2.0-10.0 g/m², 2.5-10.0 g/m²,3.0-10.0 g/m², 3.5-10.0 g/m², 4.0-10.0 g/m², 4.5-10.0 g/m², 5.0-10.0g/m², 5.5-10.0 g/m², 6.0-10.0 g/m², 6.5-10.0 g/m², 7.0-10.0 g/m²,7.5-10.0 g/m², 5.0-10.5 g/m², 5.0-11.0 g/m², 5.0-12.0 g/m², or 5.0-15.0g/m².

The application may also take place by dipping the battery separator inthe additive or a solution of the additive (solvent bath addition) andsubsequently optionally removing the solvent, e.g. by drying. In thisway the application of the additive can be combined for example with theextraction often applied during separator production. Other preferredmethods are to spray the surface with additive or roller coat or curtaincoat additives on the surface of separator.

Another preferred option is to mix the additive or additives into themixture of thermoplastic polymer and optionally fillers and other agentsor additives which is used to produce the battery separators. Theadditive-containing homogeneous mixture is then formed into a web-shapedmaterial.

In certain embodiments, exemplary separators may contain one or moreperformance enhancing additives. The performance enhancing additive maybe surfactants, wetting agents, colorants, antistatic additives,UV-protection additives, antioxidants, and/or the like, and anycombination thereof.

Certain suitable surfactants are non-ionic while other suitablesurfactants are anionic. The additive can be a single surfactant or amixture of two or more surfactants, for instance two or more anionicsurfactants, two or more non-ionic surfactants, or at least one ionicsurfactant and at least one non-ionic surfactant. Selected suitablesurfactants may have HLB values less than 6, preferably less than 3. Theuse of these certain suitable surfactants in conjunction with theinventive separators described herein can lead to even further improvedseparators that, when used in a lead acid battery, lead to reduced waterloss, reduced antimony poisoning, improved cycling, reduced floatcurrent, reduced float potential, and/or the like, or any combinationthereof for that lead acid batteries. Suitable surfactants includesurfactants such as salts of alkyl sulfates; alkylarylsulfonate salts;alkylphenol-alkylene oxide addition products; soaps;alkyl-naphthalene-sulfonate salts; one or more sulfo-succinates, such asan anionic sulfo-succinate; dialkyl esters of sulfo-succinate salts;amino compounds (primary, secondary or tertiary amines; quaternaryamines; block copolymers of ethylene oxide and propylene oxide; variouspolyethylene oxides; and salts of mono and dialkyl phosphate esters. Theadditive can include a non-ionic surfactant such as polyol fatty acidesters, polyethoxylated esters, polyethoxylated alcohols, alkylpolysaccharides such as alkyl polyglycosides and blends thereof, amineethoxylates, sorbitan fatty acid ester ethoxylates, organosilicone basedsurfactants, ethylene vinyl acetate terpolymers, ethoxylated alkyl arylphosphate esters and sucrose esters of fatty acids.

In certain embodiments described herein, a reduced amount of, or evenvery little to no anionic or non-ionic surfactant is added to theinventive separator. In such instances, the ER of the inventiveseparator may be slightly higher than an inventive separator comprisingmore of the anionic or non-ionic surfactant; however, the combination ofthe lower ER versus known separators combined with the desirable featureof lowered total organic carbons (because of the lower amount ofsurfactant) may produce a desirable inventive separator according tosuch embodiment.

In certain embodiments, the additive can be represented by a compound ofFormula (I)R(OR¹)_(n)(COOM_(1/x) ^(x+))_(m)  (I)in which:

-   -   R is a non-aromatic hydrocarbon radical with 10 to 4200 carbon        atoms, preferably 13 to 4200, which can be interrupted by oxygen        atoms;    -   R¹═H, —(CH₂)_(k)COOM^(x+) _(1/x) or —(CH₂)_(k)—SO₃M^(x+) _(1/x),        preferably H, where k=1 or 2;    -   M is an alkali metal or alkaline-earth metal ion, H⁺ or NH₄ ⁺,        where not all the variables M simultaneously have the meaning        H⁺;    -   n=0 or 1;    -   m=0 or an integer from 10 to 1400; and    -   x=1 or 2.

The ratio of oxygen atoms to carbon atoms in the compound according toFormula (I) being in the range from 1:1.5 to 1:30 and m and n not beingable to simultaneously be 0. However, preferably only one of thevariables n and m is different from 0.

By non-aromatic hydrocarbon radicals is meant radicals which contain noaromatic groups or which themselves represent one. The hydrocarbonradicals can be interrupted by oxygen atoms, i.e. contain one or moreether groups.

R is preferably a straight-chain or branched aliphatic hydrocarbonradical which can be interrupted by oxygen atoms. Saturated,uncross-linked hydrocarbon radicals are quite particularly preferred.

Through the use of the compounds of Formula (I) for the production ofbattery separators, they can be effectively protected against oxidativedestruction.

Battery separators are preferred which contain a compound according toFormula (I) in which:

-   -   R is a hydrocarbon radical with 10 to 180, preferably 12 to 75        and quite particularly preferably 14 to 40 carbon atoms, which        can be interrupted by 1 to 60, preferably 1 to 20 and quite        particularly preferably 1 to 8 oxygen atoms, particularly        preferably a hydrocarbon radical of formula        R²—[(OC₂H₄)p(OC₃H₆)_(q)]—, in which:        -   R² is an alkyl radical with 10 to 30 carbon atoms,            preferably 12 to 25, particularly preferably 14 to 20 carbon            atoms;        -   P is an integer from 0 to 30, preferably 0 to 10,            particularly preferably 0 to 4; and        -   q is an integer from 0 to 30, preferably 0 to 10,            particularly preferably 0 to 4;        -   compounds being particularly preferred in which the sum of p            and q is 0 to 10, in particular 0 to 4;    -   n=1; and    -   m=0.

Formula R²—[(OC₂H₄)_(p)(OC₃H₆)_(q)]— is to be understood as alsoincluding those compounds in which the sequence of the groups in squarebrackets differs from that shown. For example according to the inventioncompounds are suitable in which the radical in brackets is formed byalternating (OC₂H₄) and (OC₃H₆) groups.

Additives in which R² is a straight-chain or branched alkyl radical with10 to 20, preferably 14 to 18 carbon atoms have proved to beparticularly advantageous. OC₂H₄ preferably stands for OCH₂CH₂, OC₃H₆for OCH(CH₃)₂ and/or OCH₂CH₂CH₃.

As preferred additives there may be mentioned in particular alcohols(p=q=0; m=0) primary alcohols being particularly preferred, fattyalcohol ethoxylates (p=1 to 4, q=0), fatty alcohol propoxylates (p=0;q=1 to 4) and fatty alcohol alkoxylates (p=1 to 2; q=1 to 4) ethoxylatesof primary alcohols being preferred. The fatty alcohol alkoxylates arefor example accessible through reaction of the corresponding alcoholswith ethylene oxide or propylene oxide.

Additives of the type m=0 which are not, or only difficulty, soluble inwater and sulphuric acid have proved to be particularly advantageous.

Also preferred are additives which contain a compound according toFormula (I), in which:

-   -   R is an alkane radical with 20 to 4200, preferably 50 to 750 and        quite particularly preferably 80 to 225 carbon atoms;    -   M is an alkali metal or alkaline-earth metal ion, H⁺ or NH₄ ⁺,        in particular an alkali metal ion such as Li⁺, Na⁺ and K⁺ or H⁺,        where not all the variables M simultaneously have the meaning        H⁺;    -   n=0;    -   m is an integer from 10 to 1400; and    -   x=1 or 2.

In certain embodiments, suitable additives may include, in particular,polyacrylic acids, polymethacrylic acids and acrylic acid-methacrylicacid copolymers, whose acid groups are at least partly neutralized, suchas by preferably 40%, and particularly preferably by 80%. The percentagerefers to the number of acid groups. Quite particularly preferred arepoly(meth)acrylic acids which are present entirely in the salt form.Suitable salts include Li, Na, K, Rb, Be, Mg, Ca, Sr, Zn, and ammonium(NR₄, wherein R is either hydrogen or a carbon functional group).Poly(meth)acrylic acids may include polyacrylic acids, polymethacrylicacids, and acrylic acid-methacrylic acid copolymers. Poly(meth)acrylicacids are preferred and in particular polyacrylic acids with an averagemolar mass M_(w) of 1,000 to 100,000 g/mol, particularly preferably1,000 to 15,000 g/mol and quite particularly preferably 1,000 to 4,000g/mol. The molecular weight of the poly(meth)acrylic acid polymers andcopolymers is ascertained by measuring the viscosity of a 1% aqueoussolution, neutralized with sodium hydroxide solution, of the polymer(Fikentscher's constant).

Also suitable are copolymers of (meth)acrylic acid, in particularcopolymers which, besides (meth)acrylic acid contain ethylene, maleicacid, methyl acrylate, ethyl acrylate, butyl acrylate and/or ethylhexylacrylate as comonomer. Copolymers are preferred which contain at least40% by weight and preferably at least 80% by weight (meth)acrylic acidmonomer; the percentages being based on the acid form of the monomers orpolymers.

To neutralize the polyacrylic acid polymers and copolymers, alkali metaland alkaline-earth metal hydroxides such as potassium hydroxide and inparticular sodium hydroxide are particularly suitable. In addition, acoating and/or additive to enhance the separator may include, forexample, a metal alkoxide, wherein the metal may be, by way of exampleonly (not intended to be limiting), Zn, Na, or Al, by way of exampleonly, sodium ethoxide.

The microporous polyolefin can be provided in various ways with theadditive or additives. The additives can for example be applied to thepolyolefin when it is finished (i.e. after the extraction) or added tothe mixture used to produce the polyolefin. According to a preferredembodiment the additive or a solution of the additive is applied to thesurface of the polyolefin. This variant is suitable in particular forthe application of non-thermostable additives and additives which aresoluble in the solvent used for the subsequent extraction. Particularlysuitable as solvents for the additives according to the invention arelow-molecular-weight alcohols, such as methanol and ethanol, as well asmixtures of these alcohols with water. The application can take place onthe side facing the negative electrode, the side facing the positiveelectrode or on both sides of the separator.

In some embodiments, the microporous polyolefin porous membrane mayinclude a coating on one or both sides of such layer. Such a coating mayinclude a surfactant or other material. In some embodiments, the coatingmay include one or more materials described, for example, in U.S. PatentPublication No. 2012/0094183, which is incorporated by reference herein.Such a coating may, for example, reduce the overcharge voltage of thebattery system, thereby extending battery life with less grid corrosionand preventing dry out and/or water loss.

Diffusion

In certain select embodiments, exemplary separators may be defined ashaving a higher diffusion rate. The diffusion rate may be measured asthe rate at which an ion is able to pass through a separator, thusdescribing the ionic flow rate through a separator. It is believed thatthe higher the porosity of a separator, the higher the diffusioncoefficient. D₂O diffusion may be analyzed using Pulsed Field GradientSpin Echo (“PFGSE”). To determine the diffusion coefficient, separatorsamples are pre-soaked in D₂O with the oil having not been extractedfrom the separator samples. The separator samples are stacked in aNuclear Magnetic Resonance (“NMR”) tube submerged in D₂O as generallyshown in FIG. 27 . The NMR tube is placed under a vacuum to remove anyair bubbles, and the diffusion coefficient in the vertical direction(through the separator samples) is monitored.

The diffusion may be calculated using the Stejskal Equation, below:

${E\left( {\delta,g,\Delta} \right)} = {{\ln\frac{E}{E_{0}}} = {{- \gamma^{2}}g^{2}\delta^{2}{D\left( {\Delta - {\delta\text{/}3}} \right)}}}$where,

-   -   E: NMR signal peak intensity    -   γ: magnetic spin ratio (depends upon nuclides)    -   g: magnetic field gradient    -   δ: applying time of field gradient        and,        D _(e) =ε/τ×D ₀        where,    -   D_(e): diffusion coefficient of a molecule inside the separator    -   D₀: diffusion coefficient of a molecule in solution    -   ε: porosity    -   τ: index of pore tortuosity.

Table 1, below, shows various diffusion coefficient values at −10° C.and 30° C., for a control separator, an inventive embodiment, and 4commercially available separators at Δ=20 ms.

TABLE 1 Sample −10° C. 30° C. Control Separator 1.7 × 10⁻¹⁰ 9.1 × 10⁻¹⁰Inventive Embodiment 1.6 × 10⁻¹⁰ 8.8 × 10⁻¹⁰ Commercial Separator #1 1.7× 10⁻¹⁰ 9.0 × 10⁻¹⁰ Commercial Separator #2 1.8 × 10⁻¹⁰ 9.0 × 10⁻¹⁰Commercial Separator #3 2.1 × 10⁻¹⁰ 1.1 × 10⁻¹⁰ Commercial Separator #41.6 × 10⁻¹⁰ 8.6 × 10⁻¹⁰

FIG. 28 shows the diffusion coefficients at −10° C. at Δ=20 ms for asolution of H₂SO₄ only, a reference separator, an inventive embodimentseparator, and an AGM separator.

FIG. 29 illustrates a pore size distribution of an inventive embodimentcompared to the commercially available separator #1. This shows that theinventive embodiment has a mean pore size of 120 nm, while thecommercially available separator has a mean pore size of only 109 nm.

FIG. 30 depicts the pore diameter distribution of an inventiveembodiment separator. FIG. 31 illustrates a chart that describes thedispersion of a new silica filler within an inventive embodimentseparator and a standard silica within a commercially separator #1.Where the box plot represents the distribution between the 25^(th)percentile (Q1) and the 75^(th) percentile (Q₃). In this chart, thelower the values, the better the silica distribution.

Friability

In certain select embodiments, exemplary separators may utilize a silicawith a higher friability as compared to that used in commerciallyavailable separators. Silica with a high friability is believed toincrease the dispersibility of the silica within the separator, which inturn allows for more oil to penetrate the separator during formation,and, upon oil extraction, leads to a better distribution of pores withinthe separator. Lower primary silica particle size is believed to resultin greater particle aggregation, which leads to increased oilabsorption. This leads to a lower average pore size and high pore volumewith a low and narrow particle size distribution. A possibly preferredembodiment has a high silica modulus (SiO₂/Na₂O) and a greaterconcentration of sodium silicate during silica processing.

FIG. 32 depicts the size of a standard silica with that of a silica usedin an inventive embodiment of the present invention. As can be seen, thenew silica possesses a lower particle size. One way to determine thefriability of the silica is to subject the silica to an ultrasonicfrequency (over 20 kHz). FIG. 33 shows the silica size before and aftersonication, and FIG. 34 depicts the particle size distribution of thenew silica and standard silica before sonication and after 30 secondsand 60 seconds of sonication.

Exemplary separators in accordance with the present disclosure also showsuperior shrinkage values in H₂SO₄. Table 2, below, shows these values.

TABLE 2 Sample Average Minimum Maximum Standard Deviation Sample #1−1.4% −2.1% −0.6% 0.3 Sample #2 −1.2% −1.6% −0.7% 0.2

EXAMPLES

The following examples further illustrate at least selected separatorembodiments of the instant invention.

In certain embodiments, the following precipitated silicas can beemployed to obtain separators according to the invention:

Median particle size 20.48 μm, mean particle size, 24.87 μm (as measuredusing Coulter LS230)

Silica samples shown below in Table 3 having the followingcharacteristics were employed in the preparation of separators:

TABLE 3 Oil Absorption Surface Area Tap Density ml/100 g m²/g g/l SilicaA 225 180 170 Silica B 275 180 140

Polyethylene separators made using the above silica had the followingproperties shown below in Tables 4 and 5:

TABLE 4 Product Properties Unit Separator 1 Separator 2 Backwebthickness mm 0.250 0.250 Silica type Silica A Silica B Si/PE ratio 2.6:12.6:1 Starting oil content % 64.0 67.0 Final oil content % 15.5 16.5Basis weight g/m² 161 157 Puncture resistance N 14.1 13.1 Porosity %61.5 65.1 Wettability Sec 49 29 ER 10 min boil mΩ · cm² 49 40 ER 20 minsoak mΩ · cm² 65 50 Elongation - MD % 23 25 Elongation - CMD % 430 484Perox 20 hrs % 388 350 Perox 40 hrs % 333 283 Acid shrinkage % −0.9 −0.8Hg-Pore Size μm 0.099 0.126

TABLE 5 Separator 3 (Corresponds to Example 3 Product in Table 9Properties Unit Below) Separator 4 Separator 5 Separator 6 ProfileRibbed PE, Ribbed PE, Ribbed PE, Ribbed PE, greater than 12 greater than12 fewer than 12 fewer than 12 major ribs, lower major ribs, lower majorribs, higher major ribs, higher rib height rib height rib height ribheight Backweb μm 250 250 250 250 thickness Silica type B A B A Si/PEratio 2.6:1 2.6:1 2.6:1 2.6:1 Starting oil % 67 64 67 64 content Finaloil % 16.0 16.3 15.0 16.7 content Coating NI (non-ionic) None NI(non-ionic) None Surfactant Surfactant Porosity % 63.8 61.7 64.4 60.6Electrical mΩ · cm² 42 50 45 62 Resistance 20 minute mΩ · cm² 43 55 4665 soak ER Wettability sec 6 39 10 73 Puncture N 12.9 14.7 12.2 13.9Resistance Elongation - % 528 419 587 383 CMD Acid % −0.7 −0.8 −0.3 −0.1Shrinkage

Additionally, in further embodiments, the following silica fillers,described below in Table 6, were employed in the separators described inTable 7, below:

TABLE 6 Silica C Silica D Silica E Silica F Oil Absorption ml/100 g 245215 270 210 Surface Area m²/g 180 130 195 180 Bulk Density g/l 100 125No data No data

TABLE 7 Separator Separator Separator Separator 7 8 9 10 Backweb mm0.200 0.206 0.200 0.201 Thickness Silica Type C D E F Si/PE ratio 2.6:12.6:1 2.6:1 2.6:1 Starting oil % 68.0 65.1 67.0 65.2 content BasisWeight g/m² 109.6 122.4 122.0 125.3 Final oil content % 15.1 16.4 15.814.9 Porosity % 65.9 63.6 65.7 63.4 ER 10′ Boil mΩ · 36 46 33 48 cm²Wettability sec 2 2 4 3 Elongation-CMD % 275 329 294 311 Puncture N 12.413.0 10.8 13.9 Resistance

Further Examples

In the following set of examples, inventive enhanced flooded separatorswere made according to various embodiments of the present invention andtested compared with a control separator. The results are shown justbelow in Table 8.

TABLE 8 Example A Example B Enhanced Enhanced Flooded Control FloodedSPEC Property Separator A Separator A Separator B (BS-DA-961-4) ProfileRibbed PE, Ribbed PE, Ribbed PE, — fewer fewer greater than 12 than 12than 12 major ribs major ribs major ribs, lower rib height Backwebthickness 0.256 0.257 0.253  0.250 ± 0.040 (mm) Puncture resistance (N)12.5 12.2 — Min. 10.0 Total oil content (%) 15.3 16.1 14.9 17.0 ± 3.0Backweb oil content (%) 14.4 14.4 — Min. 8.0 CMD elongation (%)  530(100%)  482 (100%) — Min. 150 Elongation after Perox 379 (72%) 355 (74%)— Min. 100 20 h (%) Elongation after Perox 165 (31%) — — — 40 h (%) ER10′ boil (mΩ · cm²) 71 86 65 Max. 140 Wettability (sec) 45 141 39 —Porosity (%) 64.3 57.6 65.5 60.0 ± 7.5

The results above in Table 8 show that the separator of Example Aexhibited almost 20% lower ER compared with the control separator A.Similarly, the separator of Example B exhibited more than 20% lower ERcompared with the control separator A. These desirable lower ER resultsoccurred despite the fact that the porosity percentages for theinventive separators A and B were within the tolerances (60%+/−7.5%) forthe porosity of such a separator. Thus, the novel and unexpected porestructure of the separator contributed to the lowered ER combined with aporosity percentage for the separator that is in line with (not muchmore than) the porosity of a known separator.

Additional Examples

Several separators were formed according to the present invention. Thoseseparators were compared to comparative separators. SEMs of theinventive separators were taken to image the shish-kebab formations ofthe inventive separators.

Example 1

In Example 1, an enhanced flooded separator having a backweb thicknessof 250 μm was made according to the present invention using UHMWPE,silica, and oil, and the silica used was a high oil absorption silica.An SEM of the inventive, low ER separator, was taken, see FIG. 15A.

Three shish-kebab regions, numbered Nos. 1, 2 and 3 respectively, wereidentified on the SEM of FIG. 15A, the SEM of the separator ofExample 1. Then, FTIR spectra profiles were taken of each of the threeshish-kebab regions, see FIGS. 15B-15D. The FTIR spectra taken of eachof the three shish-kebab regions (Nos. 1, 2, and 3) of the SEM of FIG.15A of the separator of Example 1 revealed the following peak positioninformation and periodicity or repetition of the shish-kebab formationsor morphology, shown in Table 9, below.

TABLE 9 Shish-kebab region number No. 1 No. 2 No. 3 Peak position 0.11720.1484 0.1094 Periodicity or 0.057 0.047 0.085 repetition of the (57 nm)(47 nm) (85 nm) shish-kebab formation

Ultimately, an average repetition or periodicity of the shish-kebabmorphology or structure was obtained, of 63 nm.

Example 2

Further, for Example 2, an enhanced flooded separator having a backwebthickness of 200 μm was made according to the present invention, in thesame manner as Example 1 above, using UHMWPE, silica, and oil, and thesilica used was a high oil absorption silica. An SEM of the inventive,low ER separator, was taken, see FIG. 16A.

Three shish-kebab regions, numbered Nos. 1, 2 and 3 respectively, wereidentified on the SEM of FIG. 16A, the SEM of the separator of Example2. Then, FTIR spectra profiles were taken of each of the threeshish-kebab regions, see FIGS. 16B-16D. The FTIR spectra taken of eachof the three shish-kebab regions (Nos. 1, 2, and 3) of the SEM of FIG.16A of the separator of Example 2 revealed the following peak positioninformation and periodicity or repetition of the shish-kebab formationsor morphology, shown in Table 10 below.

TABLE 10 Shish-kebab region number No. 1 No. 2 No. 3 Peak position0.1172 0.1406 0.07813 Periodicity or 0.057 0.047 0.085 repetition of the(57 nm) (47 nm) (85 nm) shish-kebab formation

Ultimately, an average repetition or periodicity of the shish-kebabmorphology or structure was obtained, of 63 nm.

Example 3

For Example 3, an enhanced flooded separator having a backweb thicknessof 250 μm was made according to the present invention, in the samemanner as Example 1 above, using UHMWPE, silica, and oil, and the silicaused was a high oil absorption silica. An SEM of the inventive, low ERseparator, was taken, see FIG. 17A.

Three shish-kebab regions, numbered Nos. 1, 2 and 3 respectively, wereidentified on the SEM of FIG. 17A, the SEM of the separator of Example3. Then, FTIR spectra profiles were taken of each of the threeshish-kebab regions, see FIGS. 17B-17D. The FTIR spectra taken of eachof the three shish-kebab regions (Nos. 1, 2, and 3) of the SEM of FIG.17A of the separator of Example 3 revealed the following peak positioninformation and periodicity or repetition of the shish-kebab formationsor morphology, shown in Table 11 below.

TABLE 11 Shish-kebab region number No. 1 No. 2 No. 3 Peak position0.0625 0.05469 0.04688 Periodicity or 0.063 0.073 0.085 repetition ofthe (63 nm) (73 nm) (85 nm) shish-kebab formation

Ultimately, an average repetition or periodicity of the shish-kebabmorphology or structure was obtained, of 74 nm.

Example 4

For Example 4, an enhanced flooded separator having a backweb thicknessof 250 μm was made according to the present invention, in the samemanner as Example 1 above, using UHMWPE, silica, and oil, and the silicaused was a high oil absorption silica (a different high oil absorptionsilica from the silica used in Examples 1-3 above; each of the high oilabsorption silicas used to make the separators of Examples 1-5 rangefrom about 230 to about 280 ml/100 g). An SEM of the inventive, low ERseparator, was taken, see FIG. 18A.

Three shish-kebab regions, numbered Nos. 1, 2 and 3 respectively, wereidentified on the SEM of FIG. 18A, the SEM of the separator of Example4. Then, FTIR spectra profiles were taken of each of the threeshish-kebab regions, see FIGS. 18B-18D. The FTIR spectra taken of eachof the three shish-kebab regions (Nos. 1, 2, and 3) of the SEM of FIG.18A of the separator of Example 4 revealed the following peak positioninformation and periodicity or repetition of the shish-kebab formationsor morphology, shown in Table 12 below.

TABLE 12 Shish-kebab region number No. 1 No. 2 No. 3 Peak position0.07031 0.07031 0.07813 Periodicity or 0.056 0.056 0.051 repetition ofthe (56 nm) (56 nm) (51 nm) shish-kebab formation

Ultimately, an average repetition or periodicity of the shish-kebabmorphology or structure was obtained, of 55 nm.

Example 5

For this example, Example 5, an enhanced flooded separator having abackweb thickness of 250 μm was made according to the present invention,in the same manner as Example 1 above, using UHMWPE, silica, and oil,and the silica used was a high oil absorption silica (a different highoil absorption silica from the silica used in Examples 1-3 above andfrom the silica used in Example 4 above). An SEM of the inventive, lowER separator, was taken, see FIG. 19A.

Three shish-kebab regions, numbered Nos. 1, 2 and 3 respectively, wereidentified on the SEM of FIG. 19A, the SEM of the separator of Example5. Then, FTIR spectra profiles were taken of each of the threeshish-kebab regions, see FIGS. 19B-19D. The FTIR spectra taken of eachof the three shish-kebab regions (Nos. 1, 2, and 3) of the SEM of FIG.19A of the separator of Example 5 revealed the following peak positioninformation and periodicity or repetition of the shish-kebab formationsor morphology, shown in Table 13 below.

TABLE 13 Shish-kebab region number No. 1 No. 2 No. 3 Peak position0.07031 0.0625 0.0625 Periodicity or 0.056 0.063 0.063 repetition of the(56 nm) (63 nm) (63 nm) shish-kebab formation

Ultimately, an average repetition or periodicity of the shish-kebabmorphology or structure was obtained, of 61 nm.

Comparative Example 1

A comparative polyethylene lead acid battery separator was obtained, theseparator having a backweb thickness of 250 μm. An SEM of theComparative Example 1 separator was taken, see FIG. 20A.

Three regions, numbered Nos. 1, 2 and 3 respectively, were identified onthe SEM of FIG. 20A, the SEM of the separator of Comparative Example 1.Then, FTIR spectra profiles were taken of each of those three regions,see FIGS. 20B-20D. The FTIR spectra taken of each of the three numberedregions (Nos. 1, 2, and 3) of the SEM of FIG. 20A of the separator ofComparative Example 1 revealed the following peak position informationand periodicity or repetition information regarding the crystallinestructure and/or morphology of those three regions, shown in Table 14below.

TABLE 14 Region number No. 1 No. 2 No. 3 Peak position 0.03906 0.039060.03906 Periodicity or 0.170 0.170 0.170 repetition of the (170 nm) (170nm) (170 nm) crystalline structure of morphology of the region

Ultimately, an average repetition or periodicity of the crystallinestructure or morphology of the identified regions was obtained, of 170nm.

Comparative Example 2

Another comparative polyethylene lead acid battery separator wasobtained, the separator having a backweb thickness of 250 μm. An SEM ofthe Comparative Example 2 separator was taken, see FIG. 21A.

A region of the separator SEM image, numbered No. 1, was identified onthe SEM of FIG. 21A, the SEM of the separator of Comparative Example 2.Then, an FTIR spectra profile was taken of that region, see FIG. 21B.The FTIR spectrum taken of the region (No. 1) of the SEM of FIG. 21A ofthe separator of Comparative Example 2 revealed the following peakposition information and periodicity or repetition information regardingthe crystalline structure and/or morphology of that region, shown inTable 15 below.

TABLE 15 Region number No. 1 Peak position 0.03125 Periodicity or 0.212repetition of the (212 nm) crystalline structure of morphology of theregion

Thus, the repetition or periodicity of the crystalline structure ormorphology of the identified region was 212 nm.

Comparative Example 3

Yet another comparative polyethylene lead acid battery separator wasobtained, this one commercially available from Daramic, LLC. Theseparator had a backweb thickness of 250 μm. This separator was madesimilarly to the separators described in Examples 1-5 above, but thesilica used to make this separator was not one with a high oilabsorption value.

An SEM of the Comparative Example 3 separator was taken, see FIG. 22 .Observing FIG. 22 , there were no shish-kebab formations which werecontinuously extending in the length of at least 0.5 μm or longer inthis SEM image of the polyolefin microporous membrane. Therefore, noregions were marked on the SEM or further analyzed.

Table 16 below compares the results obtained for the periodicity orrepetition of the shish-kebab regions of Examples 1-5 versus resultsobtained for Comparative Examples 1-3.

TABLE 16 Region Example Number Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 CE 1 CE 2CE 3 No. 1 57 nm 57 nm 63 nm 56 nm 56 nm 170 nm 212 nm — No. 2 47 nm 47nm 73 nm 56 nm 63 nm 170 nm — — No. 3 85 nm 85 nm 85 nm 51 nm 64 nm 170nm — — Average 63 nm 63 nm 74 nm 55 nm 61 nm 170 nm 212 nm —

For Examples 1-5, the average repetition or periodicity of theshish-kebab formations and/or crystalline structures and/or morphologieswas from 1 nm to 150 nm, preferably from 10 nm to 120 nm, and even morepreferably from 20 nm to 100 nm. That type of structure was not observedfor the separators of Comparative Examples 1-3.

Additional properties and features of the separators of Examples 1-2 and4-5 are shown below in Table 17 (whereas Table 3 above includesproperties of the separator of Example 3).

TABLE 17 Product Properties Unit Example 1 Example 2 Example 4 Example 5Profile Ribbed PE, Ribbed PE, Ribbed PE, Ribbed PE, greater than 12greater than 12 fewer than 12 fewer than 12 major ribs, lower majorribs, lower major ribs major ribs rib height rib height Backweb μm 250200 250 250 thickness Final oil % 17.1 14.3 17.0 11.3 content Porosity %62.5 65.8 58.7 65.2 Electrical mΩ · cm² 53 38 52 45 Resistance 20 minutemΩ · cm² 57 36 — — soak ER Puncture N 13.6 12.7 11.6 12.0 ResistanceWettability seconds 25 8 6 6 Elongation - % 587 470 713 616 CMD Acid %−1.4 −1.5 −0.1 −0.4 Shrinkage

Solid State NMR Examples

For two separator samples, the ratio (Si—OH)/Si of silanol groups(Si—OH) to elemental silicon (Si) was measured using the ²⁹Sisolid-state NMR technique described in great detail above. A sample ofthe separator of Example 1 was prepared for this NMR testing as well asa sample of a comparative separator, Comparative Example 4, which was acommercially available polyethylene separator from Daramic, LLC, havinga 250 μm backweb thickness, made with the same type of polyethylenepolymer and silica as the separator described above as ComparativeExample 3.

A ²⁹Si-NMR spectrum of each sample was obtained, and these spectra areincluded as FIG. 23 . The Q₂ signal was observed at ca. −93 ppm, whilethe Q₃ signal was observed at ca. −103 ppm, and the Q₄ signal wasobserved at ca. −111 ppm. Each component peak was deconvoluted as shownin FIG. 24 , and the Q₂:Q₃:Q₄ molecular ratios were calculated usingthat information from FIG. 24 , with results shown below in Table 18:

TABLE 18 Observed ²⁹Si-NMR Signal Area Ratio Molecular Ratio Q₁ Q₂ Q₃ Q₄OH Si OH/Si CE4 0 2 16 82 20 100 0.20 Example 1 0 5 17 78 27 100 0.27Number of 3 2 1 0 OH Bonding

In the results shown above, the OH/Si ratio of the separator of Example1 is 35% higher than the OH/Si ratio for the separator of ComparativeExample 4, meaning that the additional hydroxyl and/or silanol groupspresent for the silica for the inventive separator may contribute to theimproved features of the inventive separator such as its desirable porestructure and/or morphology and its low ER.

In accordance with at least selected embodiments, the separator mayinclude or exhibit performance enhancing additives or coatings,increased porosity, increased void volume, amorphous silica, higher oilabsorption silica, fillers or silica with increased friability,increased ionic diffusion, higher silanol group silica, silica with anOH to Si ratio of 21:100 to 35:100, reduced electrical resistance, ashish-kebab structure or morphology, a polyolefin microporous membranecontaining particle-like filler in an amount of 40% or more by weight ofthe membrane and ultrahigh molecular weight polyethylene havingshish-kebab formations with extended chain crystal (shish formation) andfolded chain crystal (kebab formation) and the average repetitionperiodicity of the kebab formation from 1 nm to 150 nm, decreased sheetthickness, decreased tortuosity, and/or the like, or any combinationthereof. Such inventive separators may be especially well suited forenhanced flooded batteries (EFB) built for higher performance andreliability than conventional flooded batteries, that support at leastcertain start-stop functionality, with enhanced starting power, thatmeet the ever-increasing electrical demands of many vehicles, thatprovide a longer lifespan of recovering from deep discharges, that powerelectrical loads during engine-off periods and that support a highnumber of starts per trip, with superior cycling capability, chargeacceptance and/or the ability to operate at a low state of charge and/ora partial state of charge, with tight packed components, with batteryvibration resistance, with reliable starting performance, excellentcycling ability, improved cycling of batteries operating in a low stateand/or partial state of charge, and/or longer life than traditionallead-acid batteries, and/or the like.

In accordance with at least selected embodiments, aspects or objects,there is or are provided:

-   -   A separator for a lead acid battery comprising a polyolefin        microporous membrane, wherein        -   the polyolefin microporous membrane comprises:        -   polyethylene, preferably, ultrahigh molecular weight            polyethylene, a particle-like filler, and a processing            plasticizer; wherein        -   the particle-like filler is present in an amount of 40% or            more by weight;        -   the polyethylene comprises polymer in a shish-kebab            formation comprising a plurality of extended chain crystals            (the shish formations) and a plurality of folded chain            crystals (the kebab formations) and wherein the average            repetition or periodicity of the kebab formations is from 1            nm to 150 nm, preferably less than 120 nm.    -   The above separator for a lead acid battery, wherein        -   the average repetition or periodicity of the kebab            formations is defined by: taking an image of the surface of            the polyolefin microporous membrane with a SEM, indicating            at least three rectangular regions where the shish-kebab            formation is continuously extended in the length of at least            0.5 μm or longer in the same SEM image, and specifying the            repetition or periodicity by Fourier Transform of contrast            profile projected in the vertical direction to the length            direction of the each indicated rectangular region to            calculate the average of the repetition periods.    -   The above separator for a lead acid battery, wherein        -   the filler is selected from the group consisting of silica,            precipitated silica, fumed silica, and precipitated            amorphous silica; and wherein        -   the molecular ratio of OH to Si groups within said filler,            measured by ²⁹Si-NMR, is within a range of from 21:100 to            35:100, preferably 27:100 or more.    -   The above separator for a lead acid battery, wherein        -   the processing plasticizer is selected from the group            consisting of: processing oil, paraffin-based oil, and            mineral oil.    -   The above separator, wherein        -   silica is present at the kebab formations of polymer.    -   A novel or improved enhanced flooded battery separator        comprising at least one microporous thermoplastic sheet having        at least one of an electrical resistance less than 200 mΩ·cm²,        said separator enhancing battery life, reducing internal        resistance, increasing cold cranking amps, and/or improving        uniformity in at least enhanced flooded batteries; has        performance enhancing additives or coatings, improved fillers,        decreased tortuosity, increased wettability, reduced final oil        content, reduced thickness, decreased electrical resistance,        and/or increased porosity and/or void volume.    -   The above separator, wherein the microporous thermoplastic sheet        is characterized by at least one of the following:        -   a) an average pore size of no greater than 1 μm;        -   b) an electrical resistance less than 75 mΩ·cm², or less            than 70 mΩ·cm², or less than 65 mΩ·cm², or less than 60            mΩ·cm², or less than 55 mΩ·cm², or less than 50 mΩ·cm², or            less than 45 mΩ·cm², or less than 40 mΩ·cm², or less than 35            mΩ·cm², or even less;        -   c) an electrical resistance more than 20% less than an            electrical resistance of a known separator for a flooded            lead acid battery;        -   d) a porosity greater than 50%;        -   e) a final oil content of between about 10-20% by weight, in            some embodiments, about 14-20% by weight; and        -   f) ribbing, serrated ribbing, embossed ribbing, and/or            negative cross ribs.    -   The above separator, further comprising a filler having high        structural morphology.    -   The above separator, wherein the filler is characterized by at        least one of the following:        -   a) an average particle size of 5 μm or less;        -   b) a surface area of at least 100 m²/g; and        -   c) an oil absorption rate of at least 150 ml/100 mg.    -   The above separator, wherein the filler and thermoplastic        polymer are present in a weight ratio of from 1.5:1 to 6:1.    -   The above separator, wherein the filler comprises a precipitated        silica.    -   The above separator, wherein        -   the particle-like filler is friable to such a degree that            after 30 seconds of ultrasonication, the median silica            particle size is approximately 5.2 μm or less.    -   The above separator, wherein        -   the particle-like filler is friable to such a degree that            after 60 seconds of ultrasonication, the median silica            particle size is approximately 0.5 μm or less.    -   The above separator, comprising:        -   a mean pore size of at least approximately 120 nm.    -   The above separator, comprising:        -   a diffusion coefficient of at least approximately 1.6·10⁻¹⁰            at −5° C., and        -   an electrical resistance of approximately 40 mΩ·cm2 or            lower.    -   The above separator, comprising:        -   a diffusion coefficient of at least approximately 8.8·10⁻¹⁰            at 30° C., and        -   an electrical resistance of approximately 40 mΩ·cm2 or            lower.    -   A separator for a lead acid battery comprising:        -   a polyolefin microporous membrane, wherein the polyolefin            microporous membrane comprises polyethylene, a particle-like            filler, and a processing plasticizer; wherein        -   the particle-like filler is friable to such a degree that            after 30 seconds of ultrasonication, the median silica            particle size is approximately 5.2 μm or less.    -   A separator for a lead acid battery comprising:        -   a polyolefin microporous membrane, wherein the polyolefin            microporous membrane comprises polyethylene, a particle-like            filler, and a processing plasticizer; wherein        -   the particle-like filler is friable to such a degree that            after 60 seconds of ultrasonication, the median silica            particle size is approximately 0.5 μm or less.    -   A separator for a lead acid battery comprising:        -   a polyolefin microporous membrane, wherein the polyolefin            microporous membrane comprises polyethylene, a particle-like            filler, and a processing plasticizer; wherein        -   the particle-like filler is friable to such a degree that            after 60 seconds of ultrasonication, the median silica            particle size is approximately 0.5 μm or less.    -   A separator for a lead acid battery comprising:        -   a polyolefin microporous membrane, wherein the polyolefin            microporous membrane comprises polyethylene, a particle-like            filler, and a processing plasticizer;        -   a diffusion coefficient of at least approximately 1.6·10⁻¹⁰            at −5° C., and        -   an electrical resistance of approximately 40 mΩ·cm² or            lower.    -   A separator for a lead acid battery comprising:        -   a polyolefin microporous membrane, wherein the polyolefin            microporous membrane comprises polyethylene, a particle-like            filler, and a processing plasticizer;        -   a diffusion coefficient of at least approximately 8.8·10⁻¹⁰            at 30° C., and        -   an electrical resistance of approximately 40 mΩ·cm² or            lower.    -   A separator for a lead acid battery comprising:        -   a polyolefin microporous membrane, wherein the polyolefin            microporous membrane comprises polyethylene, a particle-like            filler, and a processing plasticizer;        -   a diffusion coefficient of at least approximately 1.6·10⁻¹⁰            at −5° C., and        -   the particle-like filler is friable to such a degree that            after 30 seconds of ultrasonication, the median silica            particle size is approximately 5 μm or less.    -   A separator for a lead acid battery comprising:        -   a polyolefin microporous membrane, wherein the polyolefin            microporous membrane comprises polyethylene, a particle-like            filler, and a processing plasticizer;        -   a diffusion coefficient of at least approximately 8.8·10⁻¹⁰            at 30° C., and        -   the particle-like filler is friable to such a degree that            after 60 seconds of ultrasonication, the median silica            particle size is approximately 0.5 μm or less.    -   A separator for a lead acid battery comprising:        -   a polyolefin microporous membrane, wherein the polyolefin            microporous membrane comprises polyethylene, a particle-like            filler, and a processing plasticizer;        -   a diffusion coefficient of at least approximately 1.6·10⁻¹⁰            at −5° C., and        -   a mean pore size of at least approximately 120 nm.    -   A separator for a lead acid battery comprising:        -   a polyolefin microporous membrane, wherein the polyolefin            microporous membrane comprises polyethylene, a particle-like            filler, and a processing plasticizer;        -   a diffusion coefficient of at least approximately 8.8·10⁻¹⁰            at 30° C., and        -   a mean pore size of at least approximately 120 nm.    -   The above separator, wherein the separator comprises one or more        of a surfactant, coating, wetting agent, colorant, antistatic        additive, antioxidant, agent for reducing oxidation, and        combinations thereof.    -   The above battery separator, wherein the separator comprises at        least one surfactant, wherein such surfactant is a non-ionic        surfactant, an anionic surfactant, or a combination thereof.    -   A method of reducing internal resistance in a lead acid battery,        preferably an enhanced flooded battery, comprising providing the        above separator.    -   A novel or improved lead acid battery, preferably an enhanced        flooded battery, comprising the above separator.    -   A novel or improved vehicle comprising the above battery or        enhanced flooded battery.    -   An improved separator as shown and described herein, for a        flooded lead acid battery, preferably, an enhanced flooded lead        acid battery, the separator exhibiting lower electrical        resistance (ER) in the battery, compared with a known separator        for flooded lead acid batteries, the separator having a        shish-kebab structure, as defined herein, and the separator        exhibiting at least one of the following in the flooded lead        acid battery, preferably enhanced flooded lead acid battery:        lowered acid stratification in the battery, compared with the        known separator; lowered voltage drop in the battery, compared        with the known separator; increased cold cranking amps (CCA) in        the battery, compared with the known separator; lowered water        loss in the battery, compared with the known separator;        increased charge acceptance in the battery, compared with the        known separator; and/or overall improved battery performance,        battery life, and/or battery cycling compared with a battery        employing the known separator.    -   An improved battery separator for a flooded lead acid battery,        or an improved flooded lead acid battery, or an improved vehicle        comprising an improved flooded lead acid battery, wherein said        battery separator or battery or vehicle approximates, meets, or        exceeds the performance of an AGM battery separator and/or an        AGM battery and/or a vehicle comprising an AGM battery and AGM        battery separator.    -   Novel or improved separators, battery separators, enhanced        flooded battery separators, batteries, cells, and/or methods of        manufacture and/or use of such separators, battery separators,        flow redox separators, cells, and/or batteries, novel or        improved enhanced flooded battery separators for enhanced        flooded batteries, an improved separator for enhanced flooded        batteries and/or improved methods of using such batteries having        such improved separators, methods, systems and battery        separators for reducing internal resistance, enhancing battery        life, reducing water loss, reducing internal resistance,        increasing wettability, reducing acid stratification, improving        acid diffusion, improving cold cranking amps and/or improving        uniformity, separators that include or exhibit performance        enhancing additives or coatings, increased porosity, increased        void volume, amorphous silica, higher oil absorption silica,        higher silanol group silica, silica with an OH to Si ratio of        21:100 to 35:100, reduced electrical resistance, a shish-kebab        structure or morphology, a polyolefin microporous membrane        containing particle-like filler in an amount of 40% or more by        weight of the membrane and ultrahigh molecular weight        polyethylene having shish-kebab formations with extended chain        crystal (shish formation) and folded chain crystal (kebab        formation) and the average repetition periodicity of the kebab        formation from 1 nm to 150 nm, decreased sheet thickness,        decreased tortuosity, and/or the like, separators especially        well-suited for enhanced flooded batteries, and/or the like as        shown or described herein.

In accordance with at least selected embodiments, aspects or objects,disclosed herein or provided are novel or improved separators, batteryseparators, enhanced flooded battery separators, batteries, cells,and/or methods of manufacture and/or use of such separators, batteryseparators, enhanced flooded battery separators, cells, and/orbatteries. In accordance with at least certain embodiments, the presentdisclosure or invention is directed to novel or improved batteryseparators for enhanced flooded batteries. In addition, disclosed hereinare methods, systems and battery separators for enhancing battery life,reducing internal electrical resistance, increasing cold cranking amps,and/or improving uniformity in at least enhanced flooded batteries. Inaccordance with at least particular embodiments, the present disclosureor invention is directed to an improved separator for enhanced floodedbatteries wherein the separator has performance enhancing additives orcoatings, improved fillers, decreased tortuosity, increased wettability,reduced oil content, reduced thickness, decreased electrical resistance,and/or increased porosity, and where the use of such a separator in abattery reduces the water loss of the battery, lowers acidstratification of the battery, lowers the voltage drop of the battery,and/or increases the CCA of the battery. In accordance with at leastcertain embodiments, separators are provided that include or exhibitperformance enhancing additives or coatings, increased porosity,increased void volume, amorphous silica, higher oil absorption silica,fillers or silica with increased friability, increased ionic diffusion,higher silanol group silica, silica with an OH to Si ratio of 21:100 to35:100, silica with an OH to Si ratio of at least 27:100, reducedelectrical resistance, a shish-kebab structure or morphology, apolyolefin microporous membrane containing particle-like filler in anamount of 40% or more by weight of the membrane and ultrahigh molecularweight polyethylene having shish-kebab formations with extended chaincrystal (shish formation) and folded chain crystal (kebab formation) andthe average repetition periodicity of the kebab formation from 1 nm to150 nm, an average repetition periodicity of the kebab formation of 150nm or less, an average repetition periodicity of the kebab formation of120 nm or less, an average repetition periodicity of the kebab formationof 100 nm or less, having shish-kebab formations with extended chaincrystal (shish formation) and folded chain crystal (kebab formation) onat least the ribbed side and an average repetition periodicity of thekebab formation from 1 nm to 150 nm, decreased sheet thickness,decreased tortuosity, and/or the like, separators especially well-suitedfor enhanced flooded batteries, and/or the like.

The present invention may be embodied in other forms without departingfrom the spirit and the essential attributes thereof, and, accordingly,reference should be made to the appended claims, rather than to theforegoing specification, as indicating the scope of the invention.

The foregoing written description of structures and methods has beenpresented for purposes of illustration only. Examples are used todisclose exemplary embodiments, including the best mode, and also toenable any person skilled in the art to practice the invention,including making and using any devices or systems and performing anyincorporated methods. These examples are not intended to be exhaustiveor to limit the invention to the precise steps and/or forms disclosed,and many modifications and variations are possible in light of the aboveteaching. Features described herein may be combined in any combination.Steps of a method described herein may be performed in any sequence thatis physically possible. The patentable scope of the invention is definedby the appended claims, and may include other examples that occur tothose skilled in the art. Such other examples are intended to be withinthe scope of the claims if they have structural elements that do notdiffer from the literal language of the claims, or if they includeequivalent structural elements with insubstantial differences from theliteral language of the claims.

The compositions and methods of the appended claims are not limited inscope by the specific compositions and methods described herein, whichare intended as illustrations of a few aspects of the claims. Anycompositions and methods that are functionally equivalent are intendedto fall within the scope of the claims. Various modifications of thecompositions and methods in addition to those shown and described hereinare intended to fall within the scope of the appended claims. Further,while only certain representative compositions and method stepsdisclosed herein are specifically described, other combinations of thecompositions and method steps also are intended to fall within the scopeof the appended claims, even if not specifically recited. Thus, acombination of steps, elements, components, or constituents may beexplicitly mentioned herein or less, however, other combinations ofsteps, elements, components, and constituents are included, even thoughnot explicitly stated.

As used in the specification and the appended claims, the singular forms“a,” “an,” and “the” include plural referents unless the context clearlydictates otherwise. Ranges may be expressed herein as from “about” or“approximately” one particular value, and/or to “about” or“approximately” another particular value. When such a range isexpressed, another embodiment includes from the one particular valueand/or to the other particular value. Similarly, when values areexpressed as approximations, by use of the antecedent “about,” it willbe understood that the particular value forms another embodiment. Itwill be further understood that the endpoints of each of the ranges aresignificant both in relation to the other endpoint, and independently ofthe other endpoint. “Optional” or “optionally” means that thesubsequently described event or circumstance may or may not occur, andthat the description includes instances where said event or circumstanceoccurs and instances where it does not.

Throughout the description and claims of this specification, the word“comprise” and variations of the word, such as “comprising” and“comprises,” means “including but not limited to,” and is not intendedto exclude, for example, other additives, components, integers, orsteps. The terms “consisting essentially of” and “consisting of” can beused in place of “comprising” and “including” to provide for morespecific embodiments of the invention and are also disclosed.“Exemplary” means “an example of” and is not intended to convey anindication of a preferred or ideal embodiment. Similarly, “such as” isnot used in a restrictive sense, but for explanatory or exemplarypurposes.

Other than where noted, all numbers expressing geometries, dimensions,and so forth used in the specification and claims are to be understoodat the very least, and not as an attempt to limit the application of thedoctrine of equivalents to the scope of the claims, to be construed inlight of the number of significant digits and ordinary roundingapproaches.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meanings as commonly understood by one of skill in the artto which the disclosed invention belongs. Publications cited herein andthe materials for which they are cited are specifically incorporated byreference.

Additionally, the invention illustratively disclosed herein suitably maybe practiced in the absence of any element which is not specificallydisclosed herein.

What is claimed is:
 1. A lead acid battery separator for enhancedflooded batteries comprising 40% or more silica having an oil absorptionfrom 250 ml/100 g to 350 ml/100 g and polypropylene and wherein thesilica has a molecular ratio of OH to Si groups within a range of 21:100to 35:100 and a bubble flow rate of from 0.015 to 0.02 l/min; andwherein the polypropylene comprises polymer in a shish-kebab formationcomprising a plurality of extended chain crystals (shish formations) anda plurality of folded chain crystals (the kebab formations) and whereinan average repetition or periodicity of the kebab formations is from 20nm to 100 nm.
 2. The lead acid battery separator of claim 1, wherein thebattery separator has an electrical resistance (ER) of 75 mΩ·cm² orless.
 3. The lead acid battery separator of claim 1, wherein the batteryseparator further comprises polyethylene.
 4. The lead acid batteryseparator of claim 1, wherein the battery separator further comprisesultra-high molecular weight (UHMW) polyethylene.
 5. The lead acidbattery separator of claim 1, wherein the average particle size of thesilica is no greater than 25 microns.
 6. The lead acid battery separatorof claim 5, the silica having an average particle size from 15 to 25microns.
 7. The lead acid battery separator of claim 1, the silicahaving a surface area in the range of 100 m²/g to 300 m²/g.
 8. The leadacid battery separator of claim 1, wherein the silica is a precipitatedsilica, a fumed silica, or a precipitated amorphous silica.